Abstract:The evolution law of fissures caused by stress damage-flow coupling in the mining process is crucial for accurately and timely predicting and preventing coal mine water disasters.A fluid solid coupling simulation method was proposed for Shanxi Haitian Coal In-dustry,which was used to simulate the development of fractures in the floor rock layer and the accompanying seepage movement during the mining process of the upper coal seam under pressure water.The numerical results successfully reproduced the development of frac-tures,changes in permeability,and formation of water inrush channels in the floor rock layers during the mining process.The most deep-ly penetrated fractured zone appears below both sides of the goaf,rapidly extending downwards with increasing mining distance,and ulti-mately penetrating to the underlying pressurized aquifer,forming a through water inrush channel with rapidly increasing water pressure and seepage rate.The study obtained the mechanism of water breakout to the underlying confined aquifer,which can help to improve the prediction and prevention of water damage in coal mines.

Abstract:The grouting reinforcement technology for surrounding rock in coal mines is one of the important guarantees for safe and effi-cient production,and the quality of grouting materials directly affects the effectiveness of grouting reinforcement.A new type of inorganic two fluid reinforcement materials for mining was explored,and the working performance parameters of flowability,stability,setting time,and strength of material under different water cement ratios and dual slurry ratios were analyzed.The actual construction effect of grou-ting reinforcement material was explored by reinforcing the wall of Sangshuping No.2 Shaft in Hancheng Mining of Shaanxi Coal.The re-sults showed that the material has good flowability and stability when the water cement ratio of slurry A was 0.4 and the mass ratio of slurry A to slurry B was 40.0∶1.0,and the early strength is relatively high,with a compressive strength of up to 8.6 MPa.The actual grouting effect shows that it is easy to construct in grouting reinforcement of the broken wall at the top coal caving end,and has a good application effect on reinforcing the broken wall at the top coal caving end,which can effectively prevent wall fragmentation.

Abstract:The reasonable width of narrow coal pillars is a key factor in ensuring the successful implementation of gob-side entry driving below the goaf.Taking the No.8213 new open-off cut of Zhongda Yanjiahe Coal Mine as the research background,the reasonable range for the width of coal pillars is calculated theoretically to be greater than 30 m or less than 7.8 m.By using numerical simulation,it was found that the stress reached its peak when the No.8213 new cut was mined to 140 meters,indicating that the loading situation of 7 me-ters narrow coal pillar left was similar to that of the original section coal pillar.Engineering practice applications have shown that the change in the amount of separation of surrounding rock roof is relatively reasonable,and the support effect of roadway is good.The re-search results have certain reference and reference value for determining the reasonable width of narrow coal pillars in gob-side entry driving below the goaf and preventing rock burst.

Abstract:Based on the limit equilibrium theory,the development width of the fractured zone of the mining coal pillar in the irregular i-solated fully-mechanized caving working face of Dashuitou Coal Mine Branch was analyzed,and a FLAC3D numerical calculation model was established to explore the distribution characteristics of lateral support pressure in goaf.The influence of different protection coal pillar widths on the movement deformation and crack development characteristics of mining roadway was studied,and the deformation of roadway during the mining period of irregular isolated working face was measured.Research has shown that the width of coal pillar crushing zone in working face of Dashuitou Coal Mine Branch is 3.78 meters.The side abutment pressure of working face shows a stress-relaxed area,a stress-concentrated area,and an original rock stress zone starting from the wall.The width of stress-relaxed area is 14 meters.It is preliminarily determined that the width of coal pillar reserved in the mining roadway of working face is 3.8 to 9.0 meters.When the width of coal pillar is small,due to the influence of side abutment pressure,the cracks in the coal pillar develop and the bear-ing capacity is poor;as the width of coal pillar increases,its bearing capacity significantly improves;but when its width is 7 meters,there is a significant stress concentration area inside the coal pillar,and due to the high stress,the plastic zone inside the coal pillar is con-nected to the lateral goaf.Based on the deformation characteristics of different coal pillar widths in the goaf on both sides,the optimal width of the protective coal pillar is determined to be 6 meters.During the actual mining period of working face,the maximum movement of roof and floor of the mining roadway is 269 mm,and the movement of two sides is 270 mm.The convergence rate of the roadway is small,and the width of coal pillar is reasonable.

Abstract:In order to reduce the impact of mining pressure on adjacent roadway No.1103 track roadway in No.1102 working face,the roof precise directional presplitting cracks and cutting seam technology was adopted to implement pressure relief management.By stud-ying the principle of pressure relief,internal explosion load of rock mass,impact range of shock wave,and key construction parameters,reasonable parameters were determined,and actual measurements were conducted to compare the top cutting section and the non top cutting section.Through actual testing,it has been shown that the maximum displacement of roof and floor after top cutting has de-creased by 389 mm,and the displacement of two sides has decreased by 399 mm.The anchoring force of sampled anchor rods has in-creased by 13-14 kN,and the overall pass rate has reached 92％.The control effect of surrounding rock after top cutting is significant.

Abstract:To solve the problem of large deformation and prolonged deformation of surrounding rock in"three soft"coal seam roadway of Tianshuibao Coal Mine,the deformation mechanism of surrounding rock was mastered through on-site observation,laboratory testing,and numerical simulation.The influence of anchor bolt pre-tightening force on roadway supporting effect was clarified,and a reasonable pre-tightening force was determined.The research results indicate that the surrounding rock of"three soft"coal seam roadway in Tian-shuibao Coal Mine contains over 30％clay minerals,which are prone to mud deformation when exposed to water.The low strength and weak bearing capacity of surrounding rock are the main reasons for large deformation of the roadway.According to numerical simula-tions,the roof subsidence decreases by 21.3％,23.7％,and 12.1％respectively when the pre tensioning force of the anchor rod is 50,70,and 90 kN.When the pre-tightening force exceeds 70 kN,further increasing the pre-tightening force will significantly weaken the control effect on surrounding rock.Therefore,the reasonable pre-tightening force of anchor bolt is determined to be 70 kN.The industri-al test results show that by improving the supporting system and increasing the pre-tightening force of anchor bolt to 70 kN,the deform-ation of roadway is effectively controlled.

Abstract:The study area is located in the southeast of Xinmi Coalfield,with 3 layers of recoverable coal seams developed.Based on the previous geological exploration data,the coal quality characteristics of the recoverable coal seam were described,and the cleanliness lev-el of No.Ⅱ1 coal seam and NO.Ⅱ3 coal seam in the research area is class Ⅲ(relatively clean coal),which is a good clean power coal and can be used as coal for coking blending,fixed bed(solid slag discharge),fluidized bed and coal water slurry fluidized bed gasifica-tion;the cleanliness level of No.Ⅶ4 coal seam is class V(poor clean coal),and its raw coal ash content is high and the recovery rate of washed floating coal is too low.It is not suitable for clean utilization and can only be used as general power coal.

Abstract:Collapse column is an important water channels in coal mine water disasters,and collapse column water accidents have caused many major water disasters.88 collapse columns have been found in Gaohe Coal Mine,some of which have been found to have water conductivity.In order to study the hydraulic conductivity of collapse columns in Gaohe Coal Mine,data on the exposed collapsed columns in Gaohe Coal Mine were collected and organized.The collapsed columns in the mine were divided into three types:non hy-draulic,coal based hydraulic,and Ordovician hydraulic.Influencing factors of hydraulic conductivity of collapse columns were summa-rized and analyzed,and a hierarchical relationship diagram of influencing factors of hydraulic conductivity of collapse columns was es-tablished.On this basis,a comparative analysis was conducted one by one on the factors affecting the hydraulic conductivity of collapse columns in Gaohe Coal Mine,including lithological factors,runoff conditions,compaction conditions,and their sub factors.Research has found that lithology has a significant impact on the hydraulic conductivity of different layers in a collapse column,the shape of folds af-fects groundwater runoff,and water conducting collapse columns are mostly developed in the runoff zone;the smaller the size of collapse columns,the lower the development height,and the smaller its compaction effect.Water conducting collapse columns are mostly con-cealed collapse columns.The research results can provide scientific basis and theoretical support for preventing water damage caused by collapse columns in the mine.

Abstract:In order to solve the problem that it is difficult to quickly and efficiently move the unit advance hydraulic support in the coal mine,combined with the actual application scene of the unit support in the underground,a trackless towing cable lifting crawler unit support transporter that can adapt to high gas mines and thin coal seam working face roadways was developed and designed.The design concept,mechanism composition,control principle,and working process of the fast lifting and loading/unloading system and four-crawl-er steering system of the unit support transporter were elaborated in detail.The fast lifting and loading/unloading system and four-crawl-er steering system are key technologies for ensuring fast,efficient,and reliable operation of the unit support transporter.The equipment has been tested in industrial and practical operations underground in a large coal mine in China,and has good prospects for promotion and application.

Abstract:Taking the No.21105 transportation roadway of a certain mine in Shanxi Province as the research object,based on clarifying the original permanent supporting scheme of transportation roadway,a supporting scheme of segmented advance grouting anchor instead of single pillar was proposed,and the feasibility of the scheme was verified through on-site experiments.The transportation roadway was divided into four experimental stages within a 150 meters area from the mining face,and the usage of single pillars and grouting anchor cables in different stages was determined according to the rock pressure monitoring results.Five stations were set up within the distance of the transportation roadway to monitor the deformation of surrounding rock.The results show that advanced grouting anchor cables can effectively control the deformation of surrounding rock,and the deformation of surrounding rock at each monitoring station is within a safe range.The research results can provide useful reference for optimizing the supporting scheme of other mining tunnels under similar working conditions.

Abstract:In response to the problem of large section open—off cut supporting for shallow buried coal seams in the northern Shaanxi min-ing area,the No.20202 high mining height fully-mechanized mining face of Sunjiacha Longhua Coal Mine was taken as the engineering background,the open-pit support technology was studied by combining the actual geological conditions,theoretical analysis,and engi-neering practice methods on-site.The results show that the main reasons for the instability and deformation of surrounding rock in the open—off cut include the concentration of stress in surrounding rock,the destruction of roof and floor due to spontaneous combustion of coal seams,and the weakening of rock mass strength by surface water.The combined support mode of bolt,anchor cable,W-shaped steel belt,and steel woven mesh is used for supporting.At the same time,the displacement of surrounding rock in roadway is monitored and measured by combining the cross layout method and roof separation meter observation method.The monitoring results show that the displacement of roof and floor is less than 50 mm,and the displacement of two sides is less than 30 mm.The combined supporting has achieved good supporting effect,providing reference for similar complex conditions of open-off cut supporting technology.

Abstract:In order to improve coal cutting efficiency and optimize the design of picks arrangement of coal winning machine drum,a study was conducted on influence law of cutting parameters of picks on mechanical properties of coal and rock fragmentation under the combined action of double tooth.Aiming at the influence of parameters such as inclination angle,impact angle,intercept,and cutting thickness of picks on cutting load,an orthogonal experimental method was used to analyze simulated blade pick and end transverse flange pick,and the influence law of relevant factors on force of picks was obtained.And the analysis and processing were carried out u-sing range and variance,providing theoretical basis and data support for optimization design of picks of coal winning machine drum.

Abstract:The lithology around gas extraction boreholes has a significant impact on deformation and instability of boreholes.Taking No.15103 working face of Wenzhuang Coal Mine as the research background,a physical and mathematical model was constructed using UDEC numerical simulation software to study the influence of different rock types of roof on the deformation and instability of extraction boreholes.The results indicate that when the roof rock is composed of fine-grained sandstone,siltstone,mudstone,limestone,and No.12 coal,the maximum horizontal and vertical displacement values of the surrounding rock gradually increase;drilling with small deformation and good stability is beneficial for gas extraction.

Abstract:Changping Mine is located in the loess hilly and gully area,with thick coal seams and high mining intensity on the working face.The mining activities have a significant impact on the surface.To study the surface movement and deformation laws in Changping mining area,the dynamic deformation laws of the surface were analyzed based on the measured data of the 6301 working face in Liupan area.The correspondence between surface movement parameters and geological mining conditions was studied using a multi information fusion method,and the influence mechanism of geological mining conditions on surface movement parameters was obtained.Research has shown that the starting distance of rock movement in the Changping heavy-duty fully-mechanized mining face is 75 m,the average lead-ing influence distance is 118 m,the leading influence angle is 77.5°,the maximum subsidence velocity is 42.44 mm/d,and the maxi-mum subsidence velocity lag angle is 75.1°;Obtained angular parameters of surface movement and deformation,including strike bound-ary angle,uphill boundary angle,strike direction movement angle,crack angle,loose layer movement angle,etc;Further analysis shows that the coefficient of subsidence due to insufficient mining is 0.71,the coefficient of subsidence due to sufficient mining is 0.87,and the coefficient of horizontal movement is 0.22,with a main impact radius of 190 m.The research results have certain practical value for surface damage control and governance,mine production safety guarantee,and ecological environment restoration in the Jincheng mining area.

Abstract:In order to grasp the gas emission rate of fully-mechanized top coal caving working face in thick coal seam group under the occurrence conditions of Fukang Mining Area,the source separation prediction method was used to predict the gas emission and propor-tion of layered coal body,adjacent layers,top coal caving,coal cutting,and residual coal in goaf under the working face,providing a ba-sis for gas control work.The research results show that during the mining period of layered working face at the top of large trench in the east wing+676～+730 m,the proportion of gas emission from the lower layer of working face is 45.63％,the adjacent layer is 26.63％,the top coal caving is 14.34％,the coal cutting is 8.44％,and the remaining coal in the goaf is 4.96％.The maximum absolute gas e-mission from the working face is 38.08 m3/min.After taking targeted control measures,the amount of gas flowing into the working face from various gas emission sources was significantly reduced,with an exhaust gas volume of 4.18 m3/min and a return airflow speed of 1.59 m/s,which can meet the normal production needs of working face.

Abstract:In response to the problem of influence of overlying coal seam goaf and coal pillars on the stability of roadway,the No.30503 return airway of a certain mine was taken as the research object.Numerical simulation and on-site observation methods were used to an-alyze the stress distribution and failure law of roadway surrounding rock under the influence of coal pillars in overlying coal seam goaf,and the corresponding roadway layout and surrounding rock control technology were explored.The results indicate that when the angle between the central axis of mining roadway and the centerline of coal pillar is 0°,the stress concentration factors on both sides and the top of roadway are the lowest.As the distance between the roadway position and the centerline of upper coal pillar increases,the maxi-mum and minimum principal stress directions of roadway will deviate,and their magnitude will approach the stress of original rock.Mo-reover,the lateral pressure coefficient gradually increases,and the plastic zone will also deviate accordingly.Taking into account factors such as supporting,maintenance,and construction,the No.30503 return air roadway was horizontally arranged 25 meters below the coal pillar in the No.2 coal seam.The mining pressure in the experimental section of roadway was slightly reduced compared to before opti-mization.A combined supporting method of"rockbolt+anchor cable+steel mesh+spray"was adopted for targeted parameter design,sig-nificantly improving the stability of roadway.

Abstract:The annual power consumption of the main ventilator in a certain mine is 23 million kW·h.In order to reduce the energy consumption of the main ventilator and ensure the safety and reliability of ventilation system,a ventilation dynamic regulation system based on sensor network has been developed and configured.By collecting real-time gas and wind speed data,intelligent analysis was conducted on the production conditions of mining face,and the main ventilator speed and air volume were automatically adjusted.A 6-month application test was conducted on the No.110 and No.120 working faces of mine.The results show that the ventilation dynamic regulation system automatically adjusts the air volume based on the operating conditions of coal mining machine and changes in the con-centration of harmful gases in working face,avoiding excessive air supply.The energy consumption of main ventilator is reduced by 15.3％,and the annual electricity cost is saved by 3.15 million yuan.Meanwhile,the measured data indicates that the concentration of harmful gases such as methane and carbon monoxide in working face continues to be maintained within a safe range,verifying the relia-bility and practicality of this technology.

Abstract:Based on comprehensive geophysical exploration technology,which uses 3D seismic and transient electromagnetic methods to comprehensively detect the water accumulation in goaf of Dangshuigou Coal Mine.Elaborated on the working principles and implementa-tion processes of 3D seismic and transient electromagnetic methods,the working principles of comprehensive geophysical methods were determined,and 3D seismic method was uesd to determine that the goaf area of No.4201,No.9201,and No.9203 working faces did not change and the attribute values were normal;the goaf area in No.4 coal seam of Shangmashi was reduced and its attribute values were normal.The area of No.9 goaf in Shangmashi has increased,with abnormal attribute values.A new goaf in Quan'an Xiaoyao has been added,with abnormal attribute values.Further detailed measurements were conducted using transient electromagnetic method to deter-mine three small kiln mining areas.There are 6 locations in goaf water accumulation area,including 2 locations in No.4 coal seam with a total area of 225 543 m2,and 4 locations in No.9 coal seam with a total area of 41 075 m2;there are 3 locations in goaf area,including 1 location in No.4 coal seam with a total area of 35 918 m2,and 2 locations in No.9 coal seam with a total area of 90 422 m2.The rele-vant conclusions can provide a basis for the treatment of water accumulation in the mine goaf.

Abstract:Scraper conveyor is the main conveying equipment of coal transportation system in fully-mechanized mining face.Scraper chain is an important carrier for its power transmission,which directly affects the normal operation of underground transportation system.In order to ensure the normal use of scraper conveyor and the reasonable tension state of scraper chain,it is particularly important.By e-laborating on the automatic tensioning system of the scraper conveyor chain and introducing the working principle and composition of the new automatic tensioning system,a comprehensive study on the automatic tensioning system of the scraper conveyor chain will help pro-mote the development of automatic control of the tension force of the scraper conveyor chain,and have a certain promoting effect on the intelligent automation construction of comprehensive mining equipment in the coal mining industry.

Abstract:Based on the engineering background of gob-side entry retaining in the No.15202 working face of Erjing Coal Mine,the roof movement process and failure structure after mining were analyzed,the axial failure length,lateral failure length,and width of the plastic zone on the side of the actual coal body from a mechanical perspective were solved,a mechanical model was established for for the com-bination of the key block of the roof and the filling body,and reasonable supporting resistance of the filling body was calculated.On this basis,a numerical model was established to analyze the stability characteristics of the surrounding rock during the mining process from the perspective of the plastic zone,the feasibility of gob-side entry retaining was further verified.Finally,after conducting industrial tests on site,and the deformation of the surrounding rock was monitored.The results indicate that the maximum deformation of the roadway is 351 mm,ensuring safe and efficient production in the mine.